Hello Momwithhope and welcome .
Glad you found us... .sorry you had to. You have certainly come to the right place to find "practical advice." I so wish I could point you to the "magic button" that, once pushed, will make everything better. Sadly, no such button. Life with our BPD'ers is, indeed, time-consuming to say nothing about hurtful at times. If only they would realize that we, their parents, only want the best for them and want to save them from the consequences of their actions. That is a pipe dream!
Our daughter (now 51) started using marijuana when she was in her early teens. Before that she was a fun-loving child... .a joy for us. We know she dabbled with other drugs, too. Even though today we are confident that she is a non-user (more of a hypochondriac) we feel damage was done at that early age. While some developing brains can come out of those times of experimentation unscathed, others can't. That could well be the case with our daughter... .maybe yours, too.
There will be others responding to your post with good suggestions/advice on how to deal with your daughter, my focus is more on YOU. It is so important that you do your homework, empower yourself. Carry no guilt because you have done the best you could along the way with the information you had... .and as you learn differently... .you will do differently.
I'm sure all of us will agree that it is heartbreaking to watch our children make choices that we know will lead to bad consequences but sometimes... .sometimes... .those consequences have to happen to them in order for them to learn. Bottom line... .we can't force change on them... .but we can change us and the way we approach them. (See Lesson 2

"If your current approach is not working, change it." This is not what any of us planned for our lives... .for our children's lives... .but this is it!
So, Momwithhope, there really is hope but I will repeat that you have to look after yourself and by implementing some of the tools to the right

you will get more of a feeling of empowerment.
Hope you stick with us! We learn from each other. You are not alone.
Huat